Whereas the cholesterol-lowering action of plant sterols and their derivatives has been well established, more recent results have produced new information concerning the similar effects of various mixtures and dose-response relationships. Moreover, although these materials have generally been viewed as safe for long-term use in almost all sectors of the population, some concerns remain regarding the impact of phytosterol consumption on other lipid-soluble nutrients, which need to be further addressed. Further work is also required to define the relationship between plant sterol consumption, circulating sterol levels, and risk of certain cancers.